Cured-in-place pipe (CIPP) repair has been used to repair damaged main sewer pipes or lateral sewer pipes as well as other types of conduits. Generally, a liner tube is impregnated with a resinous material and is positioned in a pipe adjacent a damaged area of pipe. The liner tube is pressed against the wall of the damaged area of the pipe and the resin is allowed to cure, thus leaving a renewed pipe wall. The liner tube is either pulled in place or inflated and inverted into the pipe to the damaged area in need of repair.
At times, only a specific section of a lateral pipe needs repaired. The impregnated liner tube must be either inflated and inverted, or pulled through the access pipe to the exact position of the area in need of repair. One way this is accomplished is by positioning the liner tube at a specific, predetermined location within a bladder tube. The bladder tube is inflated and the bladder and liner tubes are inverted into the lateral pipe in need of repair.
One problem that commonly arises involves the type of liner tube used to make the repair. As lateral pipes extend from main pipes, it is important when repairing lateral pipes to correctly size the liner tube and position it in the bladder tube, and to prevent longitudinal stretching of the liner tube so that the liner tube does not extend into the main pipe. If the liner tube does extend into the main pipe, the liner must be cut from the main pipe so that it does not cause blockage in the pipe. While precautions may be taken to avoid the liner tube extending into the main pipe, problems exist with the current solutions.
For example, woven scrims have been used and sandwiched between two layers of absorbent material to form a non-stretching liner tube as taught in U.S. Pat. No. 6,732,763. However, the woven scrims, while limiting longitudinal stretching, also limit radial stretching. The scrims do not allow for the liner tube to be fully pressed against the walls of pipes having bends and pipe diameter changes along the length of the pipes.
Additionally, because the amount of longitudinal stretching of the liner may be unknown, it is possible that the liner may be positioned such that all of the area in need of repair is not covered. Additional lining processes would be required, adding time and expense to the process.
Accordingly, there is a need in the art for an improved method and means of lining a lateral pipe with a CIPP liner tube that does not substantially stretch lengthwise, but allows the liner to be stretched radially and pressed fully against the damaged area of the pipe.